1. Field of the Invention
The present invention relates in general to an image processing apparatus and more particularly to an apparatus that removes undesirable effluents from the interior of a corona charging device.
2. Description of the Related Art
In a typical commercial reproduction apparatus (electrostatographic copier/duplicators, printers, electrophotographic devices, or the like), a latent image charge pattern is formed on a uniformly charged dielectric member. Pigmented marking particles are attracted to the latent image charge pattern to develop images on the dielectric member. A receiver member is then brought into contact with the dielectric member. An electric field, such as provided by a corona charger or an electrically biased roller, is applied to transfer the marking particle developed image to the receiver member from the dielectric member. After transfer, the receiver member bearing the transferred image is separated from the dielectric member and transported away from the dielectric member to a fuser apparatus at a downstream location. There, the image is fixed to the receiver member by heat and/or pressure from the fuser apparatus to form a permanent reproduction thereon. Corona charging is a common technology used to charge surfaces in electrophotographic (EP) engines. Corona devices work by ionizing air by applying a high potential on a small diameter wire or equivalent. These corona devices can also produce undesirable effluents as a result of the ionization process. These effluents can include O2 (Ozone) and NOx. Ozone can be an irritant and can attack rubber and other materials, and NOx can interact with moisture in the air to form dilute Nitric Acid which, if deposited on the surface of a photoconductor (PC), can result in image defects (Charger Rest Defect-CRD) due to lateral conductivity on the PC surface. Certain deposits can precipitate on the surface of corona wires causing non-uniform corona emission and, hence, non-uniform charging of the PC surface. The corona charger also needs to be protected from contamination that is sometimes introduced into the corona charger from other subsystems that are in the electrophotographic device; most notably, toner dust and paper fibers and filler.
Therefore, there is a need for these effluents/contamination to be eliminated/removed from the corona charger or charging device during operation. With the invention described below, effluents are directed to a secondary device(s) where the effluents can be removed from the apparatus and be catalyzed (neutralized) to improve the operation of the apparatus.
In view of the foregoing and other problems, disadvantages, and drawbacks of the conventional image processing apparatus, the present invention has been devised, and it is an object of the present invention, to provide a structure and method for an improved image processing apparatus. This invention provides an integrated charger ventilation system used to improve the reliability of the charging function. An air curtain across the mouth of a charger prevents ingestion of outside contaminants. A high flow, low velocity vacuum duct is used to exhaust corona effluents and other contaminants from the interior of the charger. A duct on the upstream side of the charger, facing the photoconductor surface of a photoconductor drum, scavenges contaminants that could enter the charger in the boundary layer created by the rotation of the photoconductor drum.
In order to attain the objects suggested above, there is provided, according to one aspect of the invention, an image processing apparatus having a photoconductive surface that receives an electrostatic charge from a charging device and a contamination control apparatus adjacent the photoconductive surface. The contamination control apparatus has an input air port and an output air port that produce an air current that removes contaminates from an area near the charging device. The air current prevents air exterior to the contamination control apparatus from entering the contamination control apparatus. The contamination control apparatus includes a pull duct that draws the contaminates from the area near the photoconductive surface. The pull duct includes an output air port for receiving contaminate particles redirected by the air current and a second opening for drawing contaminate particles from the photoconductor drum. The contamination control apparatus includes an intake duct near the photoconductive surface that removes contaminants. The air current deflects contaminants not removed by the intake duct to prevent the contaminants from entering the contamination control apparatus. During a charging of the photoconductive surface, ambient contaminants that are produced near the charging device are prevented from contaminating the photoconductive surface by the air current.
In a method embodiment, the invention processes images by charging a photoconductive surface using a charging device, providing an air current adjacent to the charging device, modifying the charge on the photoconductive surface relative to an image being processed, and transferring image marking particles to an image recording medium using the charge on the photoconductive surface. The air current removes contaminants from an area near the charging device. The air current further prevents contaminants from entering the charging device and removes contaminants from the charging device. The air current is created by an input air port and an output air port within the charging device. The input air port and the output air port form portions of sidewalls of the charging device and further draw contaminants from the photoconductive surface.
The invention provides two basic modes of contamination control. First, the invention prevents effluents created by the corona process from migrating into the rest of the EP engine and, secondly, the invention protects the charging device or corona charger from being contaminated with effluents (primarily toner dust) emitted from other subsystems in the EP engine. By using a non-contact high-velocity, low-flow airflow air curtain, the inventive contamination control system does not impede the function of the corona charger.